MILAN—Alitalia is scrambling to survive by trying to coax more cash out of Air France-KLM SA. But new capital from its industry partner wouldn't solve one of the unprofitable Italian carrier's biggest problems: the lack of a viable hub.

Many battered airlines around the globe have staged comebacks by exploiting a strong home airport. A decade ago, British Airways and Swiss International Air Lines used the high-margin business traffic generated by their hubs in London and Zurich, respectively, to turn themselves around,...